The star writes of abuse that started at home when he was only 4.

In his upcoming memoir, Coreyography (out Oct. 28), Corey Feldman is recounting a sad and sordid childhood in Hollywood.

The New York Post and Daily News report today that in the book, Feldman writes of meeting Corey Haim when they were 14 and preparing to work together on the film The Lost Boys.

The two Coreys bonded instantly.

Haim confided that on the set of the 1986 film Lucas, an adult male convinced him that it was perfectly normal for older men and younger boys in the business to have sexual relations, that it was what all the guys do. So they walked off to a secluded area between two trailers ... and Haim allowed himself to be sodomized."

Haim then followed up with a question for Feldman: "So," he said, "I guess we should play around like that, too?"

Feldman told him: "No, that's not what kids do, man."

The stars first made this revelation in 2008 on their reality show, The Two Coreys, which led the two to have a huge falling out. They stopped speaking to each other.

The man who abused Haim now "walks around, one of the most successful people in the entertainment industry, still making money hand over fist," Feldman writes, without naming the guy.

Haim died of pneumonia in 2010 at age 38, after 15 stints in rehab to combat his addiction to drugs.

Feldman also writes of his troubles at home. His mother, Sheila, was a former Playboy model with severe depression and drug issues, who verbally abused Feldman starting at age 4, calling him fat and force-feeding him diet pills. The abuse turned physical and she, at one point, said to him, "I'm going to kill you ..."